A Diminished
Hear the A Diminished chord played for you.
A°
A – C – D♯
Formula:R-m3-d5
Intervals:P1-m3-d5
Scale Degrees:1-b3-b5
Introduction
The A Diminished chord is a three-note chord made up of A, C, and D♯. It is built from a root, minor third, and diminished fifth.
The A Diminished piano chord (Adim) consists of the notes A, C, D#. It is built by stacking two minor thirds (3 semitones each), giving it a tense, unstable, and dissonant character. Formula: R-m3-d5 | Scale degrees: 1-b3-b5.
Notes
A Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | A4 – C5 – D#5 |
| 1st Inversion | C5 – D#5 – A5 |
| 2nd Inversion | D#5 – A5 – C6 |
Key Signature
The key of A Diminished has 3 sharps.
F♯C♯G♯
Order of sharps
Sharps are added to a key signature in a fixed order. Each new sharp key adds the next sharp on the list.
F♯C♯G♯D♯A♯E♯B♯
Mnemonic: Father Charles Goes Down And Ends Battle
Chords in the Key of A Major
These are the diatonic triads built on each degree of the A major scale:
C
D
E
F
G
A
B
C
D
E
F
G
A
B
I — A Major (major)
Theory: Intervals
Formula: R-m3-d5
Intervals: P1-m3-d5
The A Diminished is built by stacking intervals from the root note. The formula R-m3-d5 describes the scale degrees used. The intervals P1-m3-d5 show the distance between each note in the chord.
A Diminished — Frequently Asked Questions
What notes are in the A Diminished chord?
The A Diminished chord contains: A (root), C (minor third), and Eb (diminished fifth). Both intervals are compressed: the minor third is 3 semitones above the root, and the diminished fifth is 6 semitones — a tritone.
How does A Diminished differ from A Minor?
A Minor has a perfect fifth. A Diminished lowers the fifth by one semitone to Eb (diminished fifth). That extra compression creates intense harmonic tension — the tritone between root and diminished fifth is the most dissonant interval in Western music.
What is the symbol for the A Diminished?
A Diminished is written as Adim or A°. The ° or "dim" symbol means both the third and fifth are minor/diminished. Do not confuse with Adim7 or Aø (half-diminished), which include additional notes.
What are the inversions of A Diminished?
First inversion (A Diminished/C): C–Eb–A. Second inversion (A Diminished/Eb): Eb–A–C. Diminished triads are used in classical music as the vii° chord — the chord one semitone below the tonic, with strong resolution pull.
How is A Diminished used in music?
A Diminished most commonly functions as the vii° chord in a major key, creating strong resolution back to the tonic. It also works as a chromatic passing chord between two nearby chords, and in classical music as a brief point of dissonance. Jazz uses the full four-note dim7 more often than the triad.
What songs use diminished chords?
Michelle (Beatles) uses a diminished chord as a chromatic passing chord. Many classical pieces use vii°–I cadences. Jazz standards use dim7 chords as chromatic passing and approach chords. Diminished harmony also appears in flamenco and film music for dramatic tension.
Practice Tips
- Compare A Minor and A Diminished: only the fifth changes (Eb vs perfect fifth). Play both back to back — the extra compression is striking.
- The tritone between A and Eb creates maximum tension — practice just this two-note interval to hear its characteristic sound.
- A Diminished most naturally resolves up by half step: play Adim then a chord whose root is A raised by one semitone.
- Practice all inversions: A–C–Eb, C–Eb–A, Eb–A–C.
- Use A Diminished as a vii° chord: it is one semitone below A# Major — try Adim → A# Major to feel this powerful classical resolution.
- In a major key, find where A Diminished fits naturally as a passing chord between two diatonic chords a step apart.
Related Tools
Chord FinderLook up any chord — see the notes, hear it, and play along.Chord DrillTimed drills to build speed and recognition across all chord types.Practice RoomPlug in a MIDI keyboard and get real-time feedback on every chord and scale.Circle of FifthsVisualize key relationships, relative minors, and key signatures.MIDI MonitorLive MIDI message stream with note names, velocity, and a scrolling staff.